Twitter touched off a torrent of criticism after announcing last week it can remove messages from the online service–known as tweets–within specific countries if asked to do so. Monday, Mr. Costolo said the policy was designed for the company to exist in certain countries, not as a means of censorship ….

The company is just trying to handle the situation in “the most honest, transparent and forward-looking way,” he said. “You can’t reside in countries and not operate within the law.”

The announced policy is not meant as a means for the company to get into countries where it currently isn’t, such as China or Iran. “I don’t think the current environment in China is one in which we can operate,” Mr. Costolo said.

Alex Macgillivray, Twitter’s general counsel, said in an interview on Friday that the announcement wasn’t a “policy change.” Twitter’s “philosophy is still the same” about wanting to protect free speech on the Web as much as possible, he said ….

Macgillivray didn’t delve into what Twitter would or wouldn’t agree to censor in different countries but said the announcement “has nothing to do with China,” where the company’s service has been blocked. He added that authorities there likely wouldn’t care much about Twitter’s system because the company doesn’t filter content before it is posted; rather, it responds to requests to remove tweets after users have posted them.

When asked whether Twitter would ever consider proactively filtering content before it is posted based on standing government requests in some countries, like China, Macgillivray said that while it’s “hard to say ‘ever,’ I don’t see how we could do it.”